Ignition device



May 15, 1934.

w. w STUART 1,958,773

IGNITION DEVICE Filed Sept. 2l. 1931 www Mlm/lg.:

Patented May 15, 1934 UNITED STATES PATENT OFFICE 2 Claims.

My present invention relates to a structure including an oil burner andan ignition device therefor, having a gas burner, means for lighting thegas, as by an electric spark or other means, and means for shutting offthe gas and ignition means shortly after the oil has been ignited.

The object of my invention is to provide an ignition device especiallyadapted for oil burners and of simple, durable and comparativelyinexpensive construction.

It is a further object of my invention to provide an ignition deviceconsisting of an ignition unit and automatic means for supplying gasthereto and a means for igniting the gas, such as a high tension currentto a spark gap within the unit, a glowing element, chemical means orother suitable device.

I have herein illustrated my invention as applied to an electricallyoperated oil burner, showing an electrically controlled and operated gasvalve, and an ignition device including a high tension transformer orcoil, for igniting the gas,`

whenever the burner commences to function, an automatic means beingprovided for closing the gas valve and de-energizing the transformerafter the ignition device has been operated a predetermined period oftime.

Still another purpose is to provide means for creating ignition at leastas soon as the gas flow begins.

A further purpose is to provide means for assuring a proper supply ofoxygen at the time and point of ignition to thereby minimize thefailures due to lack of oxygen at the ignition point, withoutintroducing an excessive amount of air into any one part of the oilflame.

Another purpose is to provide a structure in which there will be an aircushion to prevent fouling of parts.

Another object of my invention is in the construction and arrangementand mounting of the ignition device for allowing access and removal formaking inspection, cleaning and adjustment outside the heating plant.

With these and other objects in view, my invention consists in theconstruction, arrangement and combination of the various parts of mydevice, whereby the objects contemplated are attained, as hereinaftermore fully set forth, pointed out in my claims, and illustrated in theaccompanying drawing, in which:

Figure 1 is a sectional perspective view of a portion of a furnaceshowing a motor-driven oil burner mounted therein and my ignition deviceassociated therewith.

Figure 2 is a plan View of the ignition unit used in the system.

Figure 3 is an enlarged sectional View on the line 3 3 of Figure 1showing a gas nozzle and a spark gap.

Figure 4 is an enlarged sectional View through the ignition flame tubeshowing its connection with the hearth plate of the furnace.

Figure 5 is an electrical diagrammatic View illustrating the connectionswith the controlling circuit of the oil burner, a timing switch, anelectrically opened gas valve, a high tension trans'- former and theelectrodes of the ignition device; and Y Figure 6 is a perspective Viewof a modified 70v form of the ignition device.

On the accompanying drawing, I have used the reference character A toindicate generally a furnace. Coal burning furnaces are now beingequipped with oil burners as heat from an oil burner can be more readilycontrolled in an au'- tomaticvmanner and such an installati-on mayinclude the placing of a hearth plate 10 in place of the grates of thefurnace, the mounting of an oil burner unit B with respect to the hearthplate and the provision of a combustion chamber 12 formed of refractorymaterial.v

Heretofore various devices have been used for igniting the atomized oiland air discharged into the combustion chamber 12. l

In general, this oil and air are delivered to the chamber 12 by theburner B with which is asso` ciated the motor 14.

The automatic operation of the burner B is such that when the roomtemperature rises to a predetermined degree, the burner is shut off andwhen the room temperature lowers to another predetermined degree, theoil burner is turned on. When the burner is turned on, the pilot lightor some other means has heretofore been depended upon for igniting theflow of atomized oil and air.

A good many problems arise in connection with pilot lights, the rst ofwhich is that the light must be of substantial size so as not to lbeblown out by the oil and air discharged into the com-i bustion chamberl2 and yet must be small enough to consume a minimum amount of gas toprevent excessive gas bills. It has been found that pilot lights ofsufficient size to insure ignition at all times consume a prohibitiveamount of gas.

Where a pilot light is used, the gas frequently cakes in the passagesand as the coke accumulates the gas flame is reduced in size until it iseasily lown out or is too small to ignite the incoming oil.

Where an expanding gas pilot is used, wax and other impurities oftenclose the by-pass that supplies gas for the standing pilot. The tips orpilot castings of continuously burning gas pilots are often destroyedduring the normal operation of the burner.

Many other forms of igniters have vital parts in the oil stream and areoften injuriously affected by the oil stream, or interfere withcombustion. Many of them are limited to igniting of the higher grade andmore expensive oils. Often they are difficult to remove or replace,especially when the combustion chamber is hot.

I have provided an igniter which is not subject to these objections.

My ignition device consists of a mounting flange 16 adapted to besecured to the hearth plate '10 by means of bolts 18 or the like. Anignition flame tube or hearth tube 20 is welded or otherwise xed withinthe flange 16 as best shown in Figure 4. The flange 16 is embeddedbeneath the refractory combustion chamber 16 and the hearth tube 20communicates with an opening 22 formed therein which forms a dischargenozzle for the tube 20.

A casing 24 is provided with a neck 26 detachably connected with thehearth tube 20 by means of set screws 28 or the like. One end of thecasing 24 is closed while the opposite end thereof is provided with aclosure plate 3G having an aligning sleeve 32 within the casing 24. Theclosure plate is held within the casing 24 by means of a leaf springlatch 34 pivoted at 36 and provided with an opening 38 adapted to fitover a pin 40 on the sleeve 32. A slot 42 is provided in the casing 24for the pin 40 to slide through when inserting the sleeve 32 in thecasing 24.

A tube 44 extends from the closure plate 30 into the casing 24 andserves for conducting gas and for supporting the pilot tip 46, mountedon the inner'end of the tube Y44. The pilot tip 46 has a dischargeopening 48 centered below the hearth tube 20.

Through the tube 44 the discharge opening 48 communicates with aconnection 50 and a tube 52 connected to a solenoid gas valve 54. Thevalve 54 is connected with a gas supply pipe 56, whereby gas underpressure such as illuminating gas V as best shown in Figure 1 and withthe nozzle 46 as best shown'in Figure 3. An air passageway 6G extendsfrom one of the tubes 58 into the discharge opening 48 while apassageway 62 extends from the other air tube 58 through the nozzle 46andv discharges air above the discharge end of the opening 48.

A spark gap indicated at 64 is provided above the discharge opening 48and the passageway 62 points toward this gap. The gap 64 is between apair of electrodes 66 which extend through insulating bushings 68 andare provided with terminal nuts '70. A pair of high tension leads '72are connected with the terminal nuts '70 and with the secondary of ahigh tension transformer '74 or with a high tension coil.

In Figure 6, I have illustrated a single electrode 66uJ which may beused instead of the two electrodes 66 for forming a spark gap betweenthe electrode 66a and the upper edge of the discharge opening 48. In anignition device of this type one of the secondary terminals of thetransformer '74 is grounded relative to the nozzle 48.

In Figure 5, I have illustrated an electrical hook-up for the ignitiondevice in which a pair of current supply wires a and b energize theburner motor 14. Suitable automatic controls are provided, of course,for energizing the wires a and b. A timing switch 76 is provided inwhich there is a normally closed switch arm '78 which is adapted to bemoved to open posii tion by a solenoid armature 80 of the dash potretarded type. This is a timing switch which when energized will supplycurrent from the wires a and b through wires c, d and e to the primarywinding of the transformer '74 and the solenoid of the gas valve 54. Theretarded armature 80, after a predetermined length of time, raises theswitch arm '78 and thereafter holds it in raised position so that thevalve 54 and the transformer '74 will not function as long as the wiresa and b are energized. When they are deenergized and again re-energized,then the valve 54 will be opened and the electrodes 66 charged withelectricity for another predetermined period of time necessary forignition of the atomized oil and air from the burner B.

Other means may be used instead of the time switch for cutting off thegas and spark.

Thus it will be seen that -a large volume of gas may be supplied to theignition flame for a short time and completely out off thereafter .so asto reduce the expense of fuel for the ignition flame to a minimum.

With this large flame, it is possible to ignite as low a grade of oil asit is practical to use in a fully automatic burner. In practice, morethan one igniter is used on larger burners or where very low grade oilsare used.

The arrangement is such that there is a spark as soon as the gas flowbegins. Oxygen is supplied just at the point of ignition where it mustbe had. Gas alone is difficult to ignite. No unnecessary air is suppliedto any part of the oil flame. The small air tubes 58 carry such'a smallamount of air that it has no detrimental effect on the oil re. If toomuch air were supplied, the surplus would travel up into the combustionchamber, and interfere with proper combustion of the oil. By introducingair at the point where it is needed, only a small air opening isnecessary. This is placed at a point in the device, such that it willnot destroy. the air cushion protecting the insulators. Thisl isimportant because back pressure from the combustion chamber oftenimmediately follows the ignition of the oil, especially in largeinstallations. If there were air holes in the plate 30, the air cushionwould be bled and destroyed. Any gas remaining at the burner nozzle froma previous opening of the valve, is washed away by the air enteringthrough the tubes 58. e

Where a pilot flame is used with an oil burner, there is a constant flowof a small supply of gas to the pilot name. The great heat of the oilflame from the main burner tends to cause the formation of coke in thepassage leading to the pilot burner.

One advantage of my construction by which the ignition flame is lightedonly for the short period necessary to establish ignition and then isclosed off, entirely, arises from the fact that after such closing offno gas is flowing through heated parts where coking might occur. Hencewith my construction, there is never any coking of the opening 48. Inaddition the continued i: moved by loosening the set screws 28.

flow of a certain amount of air through the air tubes and upwardlythrough the opening 22 contributes to keeping the parts cool.

Temporary operation of the burner can be obtained in case of failure ofthe transformer by opening the by-pass now provided in the solenoidvalve to provide a standby pilot.

For inspecting, testing and cleaning or adjusting the igniter unit, thepipe 52 may be disconnected, the spring latch 34 may be released, andthe plate 30 with the entire electrode and nozzle assembly may bewithdrawn from the casing 24, whereupon every part thereof is readilyaccessible. The entire device may be re- Ths is rarely necessary.

After withdrawal of the electrode and nozzle assembly from the casing,the pipe 52 may be again connected and the apparatus operated and testedin plain sight. All this can be done Without disturbing the properarrangement of the spark gap with relation to the nozzle.

Some changes may be made in the construction and arrangement of theparts of my device without departing from the real spirit and purpose ofmy invention, and it is my intention to cover by my claims, any modifiedforms of structure or use of mechanical equivalents, which may bereasonably included within their scope. For eX- ample, I have here shownspark gap devices as means for ignition but other suitable means, suchas glowing elements, chemical igniters and so forth might be used. Byflame lifting in the claims, I intend to cover the action contemplated,Whether the flame continues to burn above or simply spaced from thenozzle.

I claim as my invention:

1. In a structure of the kind described, a tubular casing having adischarge passage leading from its upper part adjacent one end, aclosure detachably secured to the other end, fuel supply means, an airsupply means and current conducting means all supported on said closure,a fuel nozzle located to discharge through said discharge passage at theiirst end of the casing, connected with the fuel supply means, havingair passages connected with the air supply means, and electric ignitionmeans adjacent the nozzle and near the discharge ends of the airpassages, connected and supported with the current conducting means,said casing being otherwise closed.

2. In a structure of the kind described, a casing having a dischargepassage at one end, a closure detachably secured to the other end, fuelsupply means, air supply means and current conducting means, allsupported on said closure/ a fuel nozzle located to discharge throughsaid discharge passage connected with the fuel supply means andassociated With the air supply means, and electric ignition meansadjacent to the nozzle, near the point of discharge from the air supplymeans, connected and supported with the current conducting means, saidcasing being otherwise closed.

WILLIAM W. STUART.

